A scroll compressor used in a vehicle air conditioner includes a fixed scroll and an orbiting scroll. Each of the fixed scroll and the orbiting scroll is configured of a spiral wrap that is integrally formed on one surface of a disc-like end plate. The fixed scroll and the orbiting scroll face each other while the respective wraps are engaged with each other, to cause the orbiting scroll to revolve relative to the fixed scroll. Then, a compression space formed between the respective wraps is reduced in capacity while the compression space is caused to move from the outer periphery side to the inner periphery side, thereby resulting in compression of a refrigerant. Note that the mechanism that relates to the compression of the refrigerant and includes the fixed scroll and the orbiting scroll is also referred to as a scroll compression mechanism.
During operation of the scroll compressor, the orbiting scroll and the fixed scroll each receive force, in a direction separating from each other, from the compressed refrigerant, and the orbiting scroll accordingly moves in an axial direction. As a result, a gap is formed between a front end surface (a tooth top) of the wrap of each scroll and the end plate on the opposite side, and the refrigerant is leaked from the gap, which may deteriorate performance of the compressor.
Therefore, for example, as disclosed in Patent Literature 1, it has been proposed that, to prevent the orbiting scroll from moving during the operation of the compressor, the compressed refrigerant is applied to the rear surface of the orbiting scroll to cause the orbiting scroll to float, thereby controlling the front end surface of the wrap to be constantly brought into contact with the end plate on the opposite side. Note that the control is also referred to as orbiting back-pressure control.